I'd get him to the vet asap.

Give him nothing in meantime, not even water. His system needs to settle down. There are a number of things that could cause his symptoms--some of them scary, some of them nothing serious. When Paxil puked non-stop, she had pancreatitis. A blockage could cause it, bloat could cause it, he may just not be feeling well today. Vomitting is a symptom of many things.

There's no chance he got into something toxic, is there?

I hope it's nothing serious! All paws crossed for Nanook!